Heretofore, various types of chain conveyors have been utilized to advance work holding pallets to a number of work stations. One such system is shown in U.S. Pat. No. 4,149,620 issued Apr. 17, 1979, to N. Rosenweig, wherein the links of a chain are fastened to pallets which are adapted to slide along low friction surfaces and through a number of work stations whereat sockets are moved to engate pins extending from the pallets to position each advanced pallet within a work station.
In another similar type of conveyor system, a chain is connected to a number of sub-pallets that slide along ways and which, in turn, are selectively latched to or unlatched from a like number of wheeled pallets which ride along the top surfaces of ways. In systems of this type the pallets are unlatched at a work station and then centered or located with respect to a work performing tool. An example of such a system is shown in U.S. Pat. No. 3,805,942 issued Apr. 23, 1974, to M. J. Auernhammer.
There is still a need for simple, rugged conveyor systems which are adapted to move pallets in a horizontal loop through a number of work assembly or fabricating stations. It is desirable that a system of this type minimize the number of parts to facilitate rugged construction so that the system will require only a minimum amount of maintenance or servicing. Such a system should include facilities for locking the pallets in precise positions during the time that work operations are performed on workpieces carried by or mounted in the pallets.